Matrix assembly for creasing cardboard and like materials

ABSTRACT

A matrix assembly for creasing cardboard and like materials including an elongated flexible matrix strip to which a locater strip is thermally bonded which locater strip releasably fastens the matrix strip to a creasing rule with a longitudinal channel formed in the matrix aligned with the rule edge. A double-faced pressure-sensitive adhesive tape is provided on the base of the matrix strip to bond it to a cutting plate of a press. The method and apparatus for manufacturing the matrix assembly is disclosed.

United States Patent [191 Snodgrass [45] Nov. 18, 1975 MATRIX ASSEMBLY FOR CREASING CARDBOARD AND LIKE MATERIAIS Inventor: Frank M. Snodgrass, St. Annes-on-Sea, England Assignee: IPC, Incorporated, Martinsburg, W.

Filed: Feb. 1, 1974 Appl. No.: 438,673

Foreign Application Priority Data July l9. 1973 United Kingdom 34374/73 US. Cl. 9.3/59 R; 93/58 ST; 93/58.3 Int. Cl. B26D 3/08 Field of Search 76/107 R, I07 C; 93/58 R.

93/58 ST, 58.2 F, 58.2 R, 58.1, 58.3, 59 R References Cited UNITED STATES PATENTS lO/l950 Dalsemer 93/58 R 3.l H.898 l2/l963 Truss 93/58 R Primary E.t'aminer-R0y Lake Assistant E\'uminer-.|ames F. Coan Armrucy, Agent, or Firm-Darby & Darby ABSIRACT A matrix assembly for creasing cardboard and like materials including an elongated flexible matrix strip to which a locater strip is thermally bonded which locater strip releasably fastens the matrix strip to a creasing rule with a longitudinal channel fonned in the matrix aligned with the rule edge. A double-faced pressure-sensitive adhesive tape is provided on the base of the matrix strip to bond it to a cutting plate of a press. The method and apparatus for manufacturing the matrix assembly is disclosed.

6 Claims, 13 hawing Figures US. Patent Nov. 18, 1975 Sheet 1 of3 3,919,924

U.S. Patent Nov. 18, 1975 Sheet 2 of 3 3,919,924

FIG. 8

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Sheet 3 of 3 US. Patent Nov. 18, 1975 MATRIX ASSEMBLY FOR CREASING CARDBOARD AND LIKEMATERIALS BACKGROUND OF THE INVENTION This invention relates generally to scoring or creasing card-like material and, more particularly, to a matrix assembly for use in forming creases in cardboard carton blanks.

Card-like material is scored or creased to facilitate folding into its final shape by pressing it between a creasing rule and a scoring matrix strip, which is a long flexible strip having longitudinally formed in it a channel slightly wider than the creasing rule and in aligned position with the creasing rule edge, so that on closing the press the rule edge urges the portion of the card comprising the crease into the matrix channel, providing a well defined score line. Of course, the matrix channel must be essentially exactly aligned with the creasing rule edge.

In order to precisely align the matrix channel with the associated creasing rule, an elongate locater strip has in the past been fixed to the matrix so that the resulting assembly may be releasably coupled to the creasing rule, which is fixed to a press platen. The rule and assembly would be advanced toward the opposed cutting plate of the press, and the matrix assembly would be pressed against the cutting plate. A double-faced pressure-sensitive adhesive tape provided on the base of the matrix strip then holds the matrix strip onto the cutting plate. The locater strip would then be separated from the matrix leaving the matrix alone on the cutting plate, in alignment with the rule.

The creasing matrix-locater strip assembly has in the past constituted a relatively complex structure and, consequently, the method and apparatus for its manufacture has been correspondingly complicated. For example, in one available matrix-locater assembly, the matrix strip itself comprises an assemblage formed by a pair of narrow plastic strips fastened to a wider steel strip defining a channel between the plastic strips. A double-faced adhesive tape connects a plastic locater strip to the plastic matrix strips. The base of the steel strip is provided with a double-faced adhesive tape for securing to the cutting plate. By virtue of the number of elements comprising the matrix assembly, the method and apparatus utilized for its construction are relatively involved.

SUMMARY OF THE INVENTION Accordingly, one object of the invention is to provide a new and improved self-locating matrix assembly for creasing card-like material, as in forming blanks for cartons.

Another object of the present invention is to provide a new and improved self-locating creasing matrix assembly of relatively simple construction.

Yet another object of the present invention is to provide new and improved method of manufacturing a self-locating creasing matrix assembly.

Still another object of the present invention is to provide new and improved apparatus for manufacturing a self-locating matrix assembly.

Briefly, in accordance with a preferred embodiment of this invention, these and other objects are obtained by extruding a unitary matrix strip having a longitudinal channel formed therein from a hard, semi-flexible plastic material. A locater strip is extruded from a soft, flex- 2 ible plastic and is thermally bonded to the matrix strip in a predetermined aligned relationship. A doublefaced adhesive tape is then provided on the base of the matrix strip, being covered with a removable paper backing.

DESCRIPTION OF THE DRAWINGS A more complete appreciation of the invention and its attendant advantages will be attained by reference to the following detailed description when considered in connection with the accompanying drawings in which:

FIG. 1 is a perspective view, partly in section ofa matrix assembly according to the present invention;

FIG. 2 is an end view in section of the matrix assembly of FIG. 1;

FIG. 3 is an end view of the matrix assembly of FIG. I coupled to a creasing rule and showing their relation to a press cutting plate;

FIG. 4 is a view similar to FIG. 3 with the creasing rule advanced so that the matrix assembly is in contact with the cutting plate;

FIG. 5 is a view similar to FIG. 4 with the creasing rule withdrawn from the matrix assembly leaving it fixed on the cutting plate;

FIG. 6 is a view similar to FIG. 5 with the locater strip of the matrix assembly removed from the matrix strip;

FIG. 7 is an end view in section of another embodiment of matrix assembly according to the present invention;

FIG. 8 is a front view of apparatus for forming the locater strip of the matrix assembly;

FIG. 9 is a view in section of one portion of the apparatus of FIG. 8 taken along line 9--9 thereof;

FIG. I0 is a sectional view of another portion of the apparatus of FIG. 8 taken along line I0I0 thereof;

FIG, 11 is a schematic side view of an apparatus for bondingthe locater strip to the matrix strip;

FIG. I2 is a sectional view of a portion of the apparatus shown in FIG. II taken along line 12-12 thereof; and

FIG. 13 is an enlarged sectional view of another portion of the apparatus shown in FIG. 11 taken along line 13-13 thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings (wherein like reference numerals designate identical or corresponding parts throughout the several views) and more particularly to FIGS. 1 and 2, the matrix assembly, generally denoted as 10, comprises a matrix strip 12, a locater strip 14 on the upper surface of the matrix strip, a double-faced pressure-sensitive adhesive tape 16 provided over the base I8 of matrix strip 12, and a cover strip 20 covering the lower surface of the adhesive tape 16.

The matrix strip 12 comprises a relatively thin, elongate plastic strip having a channel 22 formed along its longitudinal axis. It is preferably formed of a hard, semiflexible polymer material (such as a polypropylene polymer or copolymer). For example, one suitable material comprises a copolymer in which propylene is the dominant monomer, namely Propathene GSE lll", manufactured by Imperial Chemical Industries, Ltd., of Great Britain. Channel 22 is slightly wider than the width of the creasing rule (FIGS. 3-6) and is sufficiently deep so that the card material when urged into the channel by the creasing rule will be permanently 3 scored along the line defined by the channel. For exarnple, the width W of strip 12 may be about 1.2 cm and its depth D about 0.5 mm. The depth of channel 22 is about 60 to 90% of the matrix strip depth. Of course. other dimensions may be found to be desirable depending upon the circumstances.

Preferably, the matrix strip 12 is manufactured by first extruding a continuous strip of the polymer material having a rectangular cross section with the desired dimensions. A channel 22 is formed in the extrusion, preferably in the manner described in detail below. According to the present invention, the upper surface 24 of the matrix strip is substantially planar so as to provide a mating surface for the locater strip 14, as will be described. It should be understood. however. that other configurations of the upper surface of the matrix strip. such as that shown in FIG. 7, are within the scope of the present invention so long as it conforms to the geometry of the corresponding surface of the locater strip.

Still referring to FIGS. I and 2, locater strip 14 comprises an elongate strip of flexible polymer material which is relatively softer than the material utilized in the manufacture of the matrix strip. For example. a copolymer of ethylene and vinyl acetate such as that known by the tradenamc Alkathene. manufactured by Imperial Chemical Industries Ltd., of Great Britain, has been found to be satisfactory. The locater strip is defined by a pair of spaced. opposed walls or ribs 26, 26' whose inner surfaces define a tapered slit 28 which terminates in a substantially oval portion 30. A pair of planar flanges 32, 32' extend laterally from the base of walls 26, 26' preferably to the same width as matrix strip 12. As noted above, however. the geometry of the lower surface 34 of the locater strip need not be identical to that shown in FIG. 2 so long as it corresponds to the particular geometry of the upper surface 24 of the matrix strip 12. In the present illustration, the lower surface 34 of locater 14 is substantially planar to cooperate with the upper planar surface 24 of the matrix strip. However, other geometries are possible. For example, as shown in FIG. 7, matrix 12' may have a sloping or substantially triangular cross section with the upper surface 24' tapering upwardly. Correspondingly, the locater strip 14' would then be formed having correspondingly tapering lower surfaces 34 to mate with the matrix strip. This configuration also provides several desirable features. The two elements inherently align themselves relative to each other because of the cooperating wedging surfaces 24 and 34'. Also, the peripheral edges of matrix 12', when secured to a cutting plate 40, do not interfere with the positioning of carton blanks on it.

The locater strip is preferably extruded in a continuous manner similar to the matrix strip. In the case of the locater strip. however. the shape of extrusion is in final form. that is, no other forming step is necessary subse' quent to the extrusion. The matrix strip is bonded to the locater strip by heating the peripheral edges of the lower surface 34 of the latter to substantially or nearly the melting point of the plastic material of which it is made causing it to soften or smear. In the example given above, these edges are heated to a temperature in the range of about 210 to 220C. When the peripheral edges of the upper surface 24 of the matrix strip is brought into contact with the locater strip a bond is created which joins the two elements together. It is essential that. upon completion of the matrix assembly.

4 slit 28 should directly overly and be aligned with channel 22. i

A double-faced pressure-sensitive adhesive tape I6 is applied over the lower surface I8 of matrix strip I2. One adhesive which may be used is known by the tradename Scotchbrand 465" available from Minnesota Mining and Manufacturing Corporation. This tape provides an effective bond with the lCl GSE-l l 1 material when cold. The bond may be improved, however. by vulcanizing the assembly during manufacture at about l60 to C. Of course, still other adhesive materials may be used. A strip 20, preferably silicone-coated paper, covers the free surface of the adhesive tape. being generally applied prior to applying the tape to the cutting plate.

Referring to FIGS. 3 through 6, the use and operation of the matrix assembly of the present invention will be described. In FIG. 3, the upper press platen 36, which supports creasing rule 38, is in its withdrawn or spaced position relative to cutting plate 40 of the press. While the press elements are in this position. the matrix assembly 10 is coupled to the creasing rule by inserting the end of creasing rule 38 into the slit 28 so that walls 26, 26 of the locater unit grasp the creasing rule and hold the matrix assembly on it. The particular geometry of the slit, described above. provides an especially good connection to the creasing rule since there is a constant pressure applied. The cover strip 20 is then peeled from the adhesive tape.

The creasing rule, together with the matrix assembly. is advanced towards cutting plate 40, until the adhesive-covered base of the assembly contacts plate 40, as seen in FIG. 4, thereby forming a bond which is stronger than the thermal bond between the locater strip 14 and matrix strip 12. The upper platen 36 is then raised. causing the creasing rule to withdrawn from slit 28, leaving the matrix assembly secured to the cutting plate as seen in FIG. 5. As noted above. channel 22 is in precise alignment with slit 28 so that channel 22 is located directly beneath the creasing rule 38. This is important since the creasing rule must urge the card material into the channel to form an adequate crease in it and even a slight misalignment will prevent this. The locater strip 14 is then peeled off the matrix strip by breaking the thermal bond. leaving the matrix strip fastened to the cutting plate as shown in FIG. 6. A cardboard blank (not shown) is then laid on the cutting plate over the matrix strip and the creasing rule and platen advanced to crease the card into a blank for subsequent folding.

Referring now to FIGS. 8-13, the apparatus for man ufacturing the matrix strip and for joining the locater strip to the matrix strip is illustrated. More particularly. FIG. 8 shows a forming machine 42 which receives an extruded plastic strip 43 slightly larger than the finished matrix strip. to allow for material contraction and for drawing. The matrix strip comprising the product of forming machine 42 may be wound on spools or directly fed into the apparatus shown in FIG. I 1, generally termed a bonding machine 44, for bonding to the locater strip.

The forming machine 42 comprises a mounting plate 46 upon which is mounted several sets of cooperating rollers whose structure is best described in connection with the operation of the machine. Forming machine 42 is located directly in line with and at a predetermined distance from the extrusion machine (not shown) which is continuously extruding a plastic strip 43 of the type described above, to a desired width and thickness equivalent to the cross-sectional area of the finished matrix strip plus a percentage allowance for material losses due to the drawing and consequent contraction of the material. The extruded strip 43 is guided through registration unit 48 between forming rollers 50, 52, being drawn off the apparatus by drawing rollers 54, 56.

The registration unit 48, best seen in FIG. 9, includes a threaded adjusting shaft 58 which is threaded into opening 60 formed in mounting plate 46. A first guide plate 62 is mounted over a reduced diameter portion of shaft 58 and is laterally constrained by a pair of retaining rings 64. A second reduced diameter threaded portion 66 of the adjusting shaft 58 constitutes an adjusting screw for an interiorly threaded knurled wheel 68 on which a second guide plate 70 is retained by a pair of retaining rings 72. A lock nut 74 is disposed over the second reduced diameter shaft portion 66 and locks the knurled wheel 68 in place. A knurled knob is fixed to the end of shaft 58. The registration unit 48 is thus designed to be laterally adjustable both in its entirety to prevent misalignment between the outlet from the extruder and the form roller 52 and, additionally, the individual guide plates are adjustable relative to each other to accommodate matrix strips of varying widths. More specifically, by manually rotating knob 76, shaft 58 and guide plate 62 are moved towards or away from the mounting plate 46. Guide rods 78 pass through both guide plates 62, 70 to facilitate this movement and to prevent binding. Second guide plate 70 may be moved relative to first guide plate 62 by loosening lock nut 74 and rotating the knurled wheel 68 to adjust the position. Lock nut 74 is then tightened to fix the second guide plate 70 in position.

After passing between the registration plates 62, 70, the plastic strip 43 passes under a roller 50, preferably formed of steel, which is rotatably mounted on a member 51 which itself is pivotally mounted on frame 46 about an axis 53. The wheel 50 and member 51 are weighted by a cantilevered arm 80 having a weight 81 adjustably mounted along its length which bears against the wheel. The position of weight 81 is adjustable in order to vary the pressures exerted by roller 50 on roller 52. For example, more pressure is required as the thickness of the plastic strip being forced into the form roller 52 is increased. Also, if a higher density polymer is employed, the pressure of roller 50 on roller 52 must be increased. the extrusion passes between form rollers 50 and 52 around an idler wheel 84 and is drawn out of the forming machine by drawing rollers 54, 56. The form roller 52 has a cross sectional shape as seen in FIG. which serves as a mold for the plastic strip which is forced evenly into the cavity 85 in roller 52 under the pressure of roller 50. The upper take-off roller 54 is vertically adjustable in order to regulate the drawing force on the matrix strip as it leaves the form rollers 52.

Both form rollers 52, 50 and take-off rollers 54, 56 may be provided with controlled variable-speed drives so that different plastic materials may be accommodated. Form roller 52 is continuously cooled externally at its point ofcontact with weighted roller 50 by air emanating from aiinozzle 86 and the roller is cooled internally by four equally spaced air jets 88.

Thus. the roughly formed extruded strip proceeds from the extruding machine through the forming machine 42 where it is shaped into the matrix strip. Subsequently, the matrix strip may proceed either directly to 6 the bonding machine 44 or to a point where it is wound onto cores to form reels which are then supplied to the bonding machine. The forming operation performed by forming machine 42 allows the strip to have extremely thin sections, particularly the section defining the bottom wall of the channel.

Referring to FIGS. ll through 13, the bonding machine 44 will now be described. Again, the structure of the machine is most conveniently described in conjunction with the description of its operation. the matrix strip 12 and locater strip 14 are fed from respective reels 90, 92 over respective heating elements 94, 96, and are aligned and bonded to each other between rollers 98 and 100. As seen in H6. 13, roller I00 has a substantially triangular cavity 102 formed in it having a protrusion or rib 104 extending upwardly in it which urges itself into the slit 28 previously formed in the locater unit. This allows the roller to pull" on the strips, exerting a tension on them as they are paid out from the reels. A roller 106 is horizontally adjustably mounted on a slidable mounting plate 107 together with heating element 96 in order to insure that the locater strip will obtain a positive connection with the roller [00, that is, to assure that the protrusion 104 formed on the surface of the roller is inserted within the passage 28 formed in the locater unit.

As seen in FIG. 12, the heating element 96 incorporates conventional heater elements such as cal-rod" heaters 97. The heating block 96 contacts only the peripheral edges of the base surface of the locater strip to cause only the plastic material in that area to soften. For the exemplified plastic material, the heater heats the plastic to about 220C. The heating element 94 is similar to heating element 96 and pre-heats the matrix strip to provide a faster connection with the locater strip.

The matrix strip and locater strip are bonded together by rollers 98 and 100. The assembly is then fed into an adhesive applicator 108 into which the adhesive tape 16 is directed. The applicator I08 applies a uniform pressure to the adhesive tape 16, affixing it to the base of the matrix strip. Finally, the matrix assembly is drawn from the bonding machine 44 by a pair of opposed rollers 110, 112 whereupon strips of a predetermined length are cut from the continuous assembly by conventional means.

Obviously, numerous modifications and variations of the present invention are possible in the light of the above teachings. [t is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise then as specifically described herein.

What is claimed is:

l. A matrix assembly for facilitating the creasing of card material by a creasing rule and opposed cutting plate comprising:

a unitary matrix strip defined by an elongate flexible plastic element having a channel formed along its longitudinal axis;

a locater strip thermally bonded to and removable from said matrix strip and defined by an elongate flexible plastic element having a slit formed along its longitudinal axis, said locater strip being positioned over and relative to said matrix strip with said slit aligned with said channel; and

an adhesive layer secured to a surface of said matrix strip for fastening said assembly to a cutting plate.

8 faces being flush with each other along the length of said assembly.

5. A matrix assembly as recited in claim 4 wherein said respective mating surfaces comprise corresponding non-planar portions.

6. A matrix assembly as recited in claim 4 wherein said respective mating surfaces are planar. 

1. A matrix assembly for facilitating the creasing of card material by a creasing rule and opposed cutting plate comprising: a unitary matrix strip defined by an elongate flexible plastic element having a channel formed along its longitudinal axis; a locater strip thermally bonded to and removable from said matrix strip and defined by an elongate flexible plastic element having a slit formed along its longitudinal axis, said locater strip being positioned over and relative to said matrix strip with said slit aligned with said channel; and an adhesive layer secured to a surface of said matrix strip for fastening said assembly to a cutting plate.
 2. A matrix assembly as recited in claim 1 wherein said slit in said locater strip has a tapered cross-section terminating in an oval shaped cavity.
 3. A matrix assembly as recited in claim 1 wherein said matrix strip is formed of a hard plastic.
 4. A matrix assembly as recited in claim 1 wherein said matrix strip and said locater strip are contiguous along respective mating surfaces, said respective surfaces being flush with each other along the length of said assembly.
 5. A matrix assembly as recited in claim 4 wherein said respective mating surfaces comprise corresponding non-planar portions.
 6. A matrix assembly as recited in claim 4 wherein said respective mating surfaces are planar. 